Classic Grilled Cheese with Marinated Onions and Whole Grain Mustard (and a Green Goddess Grilled Cheese Too!)

I think I've mentioned this before, but every time my husband flies back to New York, I tend to get a wee-bit bummed-out the next day. On his most recent trip, we spent 5 days together and his visit coincided with our Aunt Barbara's stay (fantastic) and Theodore's first birthday (that post will get written, eventually). We had an awesome date night at Root Down, had friends over for a BBQ dinner, went to the Dragon Boat Festival and hiked near Boulder on Sunday morning. Then we piled into the car and dropped him off at the airport. 
The day after he leaves I usually like to do something unexpected, or at least try to go some place where I've never been before. It gives me a sense of adventure (though most things are "an adventure" with a 1 year old and a 3 year old in tow) and it helps me keep my mind off of our current situation. 
So yesterday, the day after the airport-drop, I decided I wanted to go to another farm. It was too hot to hike and I've really taken to this farm-thing. I'd already been to Isabella Farm and Ollin. And today's destination was going to be (drum roll, please) Berry Patch Farms. Finally. 
Now friends, I learned a valuable lesson yesterday: always check the farm's hours of operation before you pack the diaper bag, assemble the snacks, load the kids in the car and head east on I-76. Yup. The farm is closed on Monday. 
We turned the car around and came back to Denver. It's not a very long trip (about 25 minutes) and we were back at our favorite playground in no time at all. But the plan to make a lunch out of the fresh produce I had anticipated buying at the farm...well, that didn't really pan out. 
I needed some comfort food...stat!
There is something really, really great (and comforting) about grilled cheese sandwiches. It's, like, the best lunch in the world. Maybe what makes them so great is the gooey cheese, the memories of childhood, or just the crunch of that grilled bread when you take a big bite. Any way you slice it, it hits the spot.
I made the Classic Grilled Cheese with Marinated Onions and Whole-Grain Mustard from Nancy Silverton's (of Mozza fame) Sandwich Book. It was so delicious! 
And since we are on the subject of grilled cheese, I decided to add a second recipe for Green Goddess Grilled Cheese too. I made it a while back, but never posted it on the enjoy that one as well!
{In case you are wondering, I went back to Berry Patch Farms today...of course, after checking their hours of operation. They were opened and we had a blast. Photos coming tomorrow, or soon thereafter.}
Classic Grilled Cheese with Marinated Onions and Whole-Grain Mustard (Courtesy of Nancy Silverton's Sandwich Book)
{Though this version on the Classic Grilled Cheese calls for only a few extra ingredients, it's a completely different sandwich. The onions and mustard salute the sensibilities of Alsace, imparting a tangy seal to this basic grilled cheese.}
Yields 4 sandwiches
For the Onions:
1/3 cup extra-virgin olive oil
2-3 tablespoons champagne vinegar or white-wine vinegar (I used 3 white-wine vinegar)
2 tablespoons of kosher salt
1 tablespoon of freshly cracked black pepper
2 medium yellow onions, sliced into 1/8-inch-thick-slices
For the rest:
8 slices white or whole-wheat sourdough bread
1/4 cup whole grain mustard
8 ounces Gruyere cheese, sliced into 24-32 1/16-inch-thick-slices (I used a peeler to get the slices thin)
To prepare the marinated onions: In a medium bowl, combine the oil, vinegar, salt, and pepper. Add the onions, toss to coat them, and allow to marinate for 15-20 minutes at room temperature. Season them with more vinegar, salt, and pepper to taste. (Mine were fine as they were.)
To assemble the sandwiches: Set half of the slices of bread buttered side down. Spread an even layer of mustard over the bread and cover with half the cheese, folding them back in toward the middle if they extend past the edges of the bread. Scatter the marinated onions on top and place the remaining cheese slices over the onions. Put the top slices of bread over the cheese, buttered side up. 
Grill the sandwiches (a few minutes in a Panini press) and cut in half on the diagonal.
* * *
This is another rocking grilled cheese sandwich. It doesn't take too long to assemble, and I had plenty of green goddess herb pesto leftover-- which I slathered on the summer squashes I picked up at the farmers market. I got a really good quality Italian bread, (courtesy of the the Denver Bread Company), and filled it with mozzarella, creamy goat cheese, sliced avocado and a big handful of spinach. Then I spread a generous amount of the green goddess herb pesto on each side and closed 'er up! The sandwich goes on the panini press for just a few minutes, until the mozzarella cheese is melted. Lunch is served and it's a good one...
Green Goddess Grilled Cheese Sandwich (Courtesy of Sarah Gim, Tastespotting)
Yields 1 sandwich
2 slices bread (we used a white bread, but one filled with lots of different whole grains and seeds would be *awesome*)
3 tablespoons Green Goddess Herb Pesto (recipe below)
2 slices mild white melty cheese like mozzarella
handful fresh baby spinach
¼ avocado, sliced
2 tablespoons goat cheese, crumbled
olive oil (and butter if you’re so inclined)
Spread about 1 tablespoon of Green Goddess Herb Pesto onto each slice of bread (2 tablespoons total, but if you’re sensitive, go light, the pesto is STRONG).
On one slice of bread, add 1 slice of cheese, sliced avocado, crumbled goat cheese, spinach, second slice of cheese, then top it with second slice of bread. Press together gently.
Heat 1 tablespoon olive oil in a frying pan over medium low heat. (If you want to use butter, add it to the oil and let it melt). Add the sandwich to the oil and cook until bread is golden brown. Press down on the sandwich lightly, then flip the sandwich over and cook until second side is golden brown.

Green Goddess Herb Pesto (Adapted from Sarah Gim, Tastespotting)
I have to say that I didn't love this pesto when I tasted it for seasoning. It was very strong. But when it was put on this, it was amazing!
1/2 clove garlic
1/2 small shallot, chopped (about 1 tablespoon)
1 1/2 teaspoon lemon juice
handful chopped fresh Italian parsley
handful chopped kale
handful of chopped spinach
1 tablespoons chopped fresh tarragon (optional)
1 tablespoon chopped chives
1/4 cup olive oil, I added another few tablespoons to get the consistency right
salt and pepper to taste
Pulse garlic and shallot in food processor until chopped. With the food processor running, add lemon juice, parsley, kale, tarragon and chives. (It won’t process very well yet, don’t worry).
Very slowly drizzle in olive oil until kale and herbs get sufficiently chopped and everything is the consistency of a pesto. You may need more or less of the olive oil depending on how big a “handful” of herbs is to you. You can also turn off the food processor and push herbs down the side of the bowl with a spatula every once in a while.
Season to taste with salt and pepper.